import type { AlertEvent, AlertRule, AlertSeverity, AlertStatus } from '../../api/types';
import { formatZhNumber } from './formatters';

const alertTimeFormatter = new Intl.DateTimeFormat('zh-CN', {
  month: '2-digit',
  day: '2-digit',
  hour: '2-digit',
  minute: '2-digit',
  second: '2-digit',
  hour12: false,
  timeZone: 'Asia/Shanghai'
});
const LEGACY_LOCAL_SQL_TIMESTAMP = /\.\d{6}Z$/;

export const severityLabels: Record<AlertSeverity, string> = { critical: '紧急', major: '重要', minor: '一般' };
export const statusLabels: Record<AlertStatus, string> = { unprocessed: '未处理', processing: '处理中', recovered: '已恢复', closed: '已关闭', ignored: '已忽略' };
export const actionLabels: Record<string, string> = { repair: '修正告警信息', trigger: '触发', acknowledge: '已确认', close: '已关闭', ignore: '已忽略', recover: '已恢复', processing: '处理中', recovered: '已恢复', closed: '已关闭', ignored: '已忽略' };
export const metricLabels: Record<string, string> = { speed_kmh: '速度', soc_percent: 'SOC', alarm_active: '协议告警位', freshness_sec: '离线时长', data_delay_sec: '数据延迟' };
export const operatorLabels: Record<string, string> = { gt: '>', gte: '≥', lt: '<', lte: '≤', eq: '=', neq: '≠', between: '区间内', outside: '区间外', changed: '状态变化' };
export const triggerTypeLabels: Record<string, string> = { metric: '数值触发', geofence: '电子围栏', stationary: '长时间静止', offline: '长时间离线' };

type AlertRuleCondition = Pick<AlertRule, 'triggerType' | 'fenceName' | 'fenceRadiusM' | 'metric' | 'operator' | 'threshold' | 'thresholdHigh' | 'valueType' | 'booleanThreshold' | 'durationSec'>;

export function formatAlertDuration(value: number) {
  if (!value) return '立即';
  if (value % 86_400 === 0) return `${value / 86_400} 天`;
  if (value % 3_600 === 0) return `${value / 3_600} 小时`;
  if (value % 60 === 0) return `${value / 60} 分钟`;
  return `${value} 秒`;
}

function ruleThresholdValue(metric: string, value: number, unit = '') {
  if (!Number.isFinite(value)) return '请设置阈值';
  if (metric === 'freshness_sec' || metric === 'data_delay_sec') return formatAlertDuration(value);
  return `${formatZhNumber(Number(value.toFixed(2)), 2)}${unit ? ` ${unit}` : ''}`;
}

export function formatAlertTime(value: string) {
  if (!value) return '—';
  // Older alert APIs appended Z to MySQL DATETIME values that were already in
  // Asia/Shanghai. Their six-digit SQL fractional seconds make the legacy
  // shape distinguishable from genuine UTC timestamps.
  const normalized = LEGACY_LOCAL_SQL_TIMESTAMP.test(value) ? value.replace(/Z$/, '+08:00') : value;
  const date = new Date(normalized);
  if (Number.isNaN(date.getTime())) return value.replace('T', ' ').slice(0, 19);
  return alertTimeFormatter.format(date).replace(/\//g, '-');
}

export function alertValue(event: Pick<AlertEvent, 'triggerValue' | 'unit'>) {
  return `${formatZhNumber(Number(event.triggerValue.toFixed(2)), 2)} ${event.unit}`.trim();
}

export function thresholdText(event: Pick<AlertEvent, 'triggerType' | 'operator' | 'threshold' | 'thresholdHigh' | 'unit' | 'durationSec'>) {
  if (event.triggerType === 'geofence') return `${{ enter: '进入围栏', exit: '离开围栏', inside: '位于围栏内', outside: '位于围栏外' }[event.operator] ?? '电子围栏条件'}${event.durationSec ? `，持续 ${formatAlertDuration(event.durationSec)}` : ''}`;
  const duration = event.durationSec > 0 ? `，持续 ${event.durationSec} 秒` : '';
  if (event.operator === 'between' || event.operator === 'outside') return `${operatorLabels[event.operator]} ${event.threshold}–${event.thresholdHigh} ${event.unit}${duration}`.trim();
  if (event.operator === 'changed') return `状态发生变化${duration}`;
  return `${operatorLabels[event.operator] ?? event.operator} ${formatZhNumber(Number(event.threshold.toFixed(2)), 2)} ${event.unit}${duration}`.trim();
}

export function alertDeltaText(event: Pick<AlertEvent, 'operator' | 'triggerValue' | 'threshold' | 'unit'>) {
  if (!Number.isFinite(event.triggerValue) || !Number.isFinite(event.threshold)) return '规则已命中';
  const delta = event.operator === 'gt' || event.operator === 'gte'
    ? event.triggerValue - event.threshold
    : event.operator === 'lt' || event.operator === 'lte'
      ? event.threshold - event.triggerValue
      : Number.NaN;
  if (!Number.isFinite(delta)) return '规则已命中';
  return `+${formatZhNumber(Number(Math.max(0, delta).toFixed(2)), 2)} ${event.unit}`.trim();
}

export function ruleCondition(
  rule: AlertRuleCondition,
  labels: Record<string, string> = metricLabels,
  units: Record<string, string> = {},
  includeDuration = true
) {
  if (rule.triggerType === 'geofence') {
    const mode = { enter: '进入', exit: '离开', inside: '位于围栏内', outside: '位于围栏外' }[rule.operator] ?? '满足围栏条件';
    return `${mode}“${rule.fenceName || '未命名围栏'}” · 半径 ${formatZhNumber(rule.fenceRadiusM ?? rule.threshold, 0)} m${includeDuration && rule.durationSec ? ` · 持续 ${formatAlertDuration(rule.durationSec)}` : ''}`;
  }
  if (rule.triggerType === 'offline') return `离线超过 ${formatAlertDuration(rule.threshold)}`;
  if (rule.triggerType === 'stationary') return `速度 ${operatorLabels[rule.operator] ?? rule.operator} ${ruleThresholdValue(rule.metric, rule.threshold, units[rule.metric] ?? 'km/h')}${includeDuration && rule.durationSec ? ` · 持续 ${formatAlertDuration(rule.durationSec)}` : ''}`;
  const unit = units[rule.metric] ?? '';
  const threshold = rule.operator === 'changed'
    ? '状态变化'
    : rule.operator === 'between' || rule.operator === 'outside'
      ? `${operatorLabels[rule.operator]} ${ruleThresholdValue(rule.metric, rule.threshold, unit)}–${ruleThresholdValue(rule.metric, rule.thresholdHigh, unit)}`
      : rule.valueType === 'boolean'
        ? (rule.booleanThreshold ? '是' : '否')
        : `${operatorLabels[rule.operator] ?? rule.operator} ${ruleThresholdValue(rule.metric, rule.threshold, unit)}`;
  return `${labels[rule.metric] ?? rule.metric} ${threshold}${includeDuration && rule.durationSec ? ` · 持续 ${formatAlertDuration(rule.durationSec)}` : ''}`;
}

export function canAct(status: AlertStatus, action: 'acknowledge' | 'close' | 'ignore') {
  if (action === 'acknowledge') return status === 'unprocessed';
  if (action === 'close') return status === 'unprocessed' || status === 'processing' || status === 'recovered';
  return status === 'unprocessed' || status === 'processing';
}